After running with compositing on with KDE 4.3 (4.2.95 = rc1) and Qt 4.5.2 for a while, the whole screen has problems repainting. That is, the whole screen goes black and starts repainting what seems like from the bottom of the z-order on up, with enough of a delay between them for me to notice (still taking less than a tenth of a second to run to completion, though). What's worse is that it doesn't really complete - it leaves portions of the screen unfinished: either it's still black, or it has something from lower in the z-order painted there (perhaps only partially itself). And then it starts the whole thing over again less than half a second later.
Turning off compositing stops this madness immediately.
I'm not sure if this is driver, xorg, Qt, or KDE, or maybe something else, but I thought I'd start here.
Radeon 3870HD, xorg-server 1.6.2, mesa 7.4.4, xf86-video-ati from git.
Can you attach your xorg log and config and a screenshot of the problem?
Created attachment 27630 [details]
xorg log file
Here's the Xorg log file. However, I can't get a screen shot - every time I run ksnapshot and tell it to take a snap shot, the whole screen gets painted properly and stays that way until after the snapshot is taken, no matter what the delay is. I'll have to grab a digital camera and take a picture of the monitors, if that'll help.
If you could still reproduce it, would you be able to get a screenshot? Getting it with a camera would be meaningful as well.
After upgrading to xorg-server 1.7, and again now with 1.8, I'm no longer experiencing this problem. (And now I'm on KDE 4.4, Qt 4.6.2, Mesa 7.8.1, too.)
I get a similar problem with only one window at a time, usually a konsole window, where it fails to repaint, and I see only whatever is behind it, and then typing something gets most of it back immediately. Not sure if it's related, but it definitely is not the full blown problem I had before.